Gas turbine engines have a combustor wherein a combustion reaction takes place to generate high temperature combustion gases to power turbines positioned downstream of the combustor. Various techniques have been devised to maintain the temperature of the combustor walls below critical levels. For example, coolant air from the compressor of the engine is often directed to the combustor walls such as along a cord side or back side thereof which is not directly exposed to the not gases of the combustion. The compressor supplies air under pressure to the combustor for both combustion and cooling purposes. Various ways of disbursing the air for the two purposes have been proposed. In the conventional arrangement, a majority of compressor air is mixed with fuel for the combustion reaction taking place within the combustor while the remaining air supplied by the compressor is utilized to cool the combustor and other engine components. It is a challenge to meet the anticipated future NOx/CO Smoke emission regulations, particularly for small aero gas turbine engines, because high pressure combustion systems must minimize compressed air utilization for combustor wall cooling and at the same time meet the greater cooling air demands of smaller combustors.
Accordingly, there is a need for an improved combustor cooling system.